1. Field of the Invention
The present invention is directed to a communications system having an ISDN central switching station coupled, via a server module, to at least one special terminal with an electroacoustical transducer, and having at least one mobile set for establishing connections to the central switching station via base stations and associated server modules. The present invention is also directed to a method for operating a communications system having an ISDN central switching station coupled, via a server module, to at least one special terminal with an electroacoustical transducer, and having at least one mobile set for establishing connections to the central switching station via base stations and associated server modules.
2. Discussion of Background Information
The cordless telephone systems of today allow the user to conduct his conversions independently of his workstation. Systems with a base station that is fixedly assigned to a mobile set, for instance via a secret code number, normally have a range of from 30 m in buildings to 300 m in the open. Other systems have base stations arranged in various service zones, and a mobile set automatically enters into communication with a base station as soon as it enters its range. The display of relevant information, such as the called number, stored numbers, charges incurred, battery status, etc., normally takes place on the mobile sets. Based on this concept, base stations can be mounted separately, outside the site and reach of the user. From International Application WO-A 90/12469, a cordless telephone system is known in which there are fewer fixed stations than mobile sets. By way of the service features of call rerouting and call rerouting tailing, made available via the private automatic branch exchange (PABX), the change of a mobile set to the radio region of a different fixed station is updated. The base stations described in European Patent Application EP-A 0 569 061 can also be provided with various identification codes, so that a plurality of mobile sets can get in contact with one base station, or individual mobile sets can contact various base stations. For the user and his work environment, it does not matter which base station the call is routed through. Communications take place solely between the bearer of the mobile set and another user. Third parties neither gain access to call-specific data nor are capable of listening in on the speech signals transmitted or entering into a conference call. This is particularly disadvantageous if the mobile set bearer is a member of a work team within which fast, problem-free data exchange is important.